Method of exsiccating unretted hemp-stalks.



C. COLAHAN.

I METHOD 0F EXSICCATING UNRETT'ED HEMPSI'ALKS.

4 APPLICATION FILED AUG. I2, 1915. .1 1,233,111

/N VEA/TQ@ Patented Ju1y17, 1917.

CHARLES COLAHAN, OF STOCKTON, CALIFORNIA.

METHOD OF EXSICCATING UNRETTED KEMP-STALKS.

Application filed August 12, 1915.

To all whom t may concern.'

Be it known that I, CHARLES COLAHAN, acitizen of the United States, and resident of Stockton, county of San Joaquin, and State of California, have invented certain new and useful improvements in the art or method of eXsiccating unretted hemp-stalks preparatory to reducing the bast to a clean fibrous condition suitable for spinning purposes.

My invention relates to the art or method employed in the first steps of originally treating the unimpaired natural stalk with its fiber, as the unbroken whole stalk is taken in bundles from the stack where it has been stored from the harvest field `to cure, and has become matured or ripened and seasoned, preserving its bright color and tensile strength which is important to maintain its natural softness and high spinning qualities, which are valuable and cannot be secured otherwise.

The object of my present invention is to preserve this natural quality of the fiber proper, in the operation of decorticating or mechanically separating it from the stalk, as the condition of the ber substance in respect to hydroscopic moisture is an important factor of such properties as make up its spinning qualities, it also seriously affects the tensile strength.

By analysis, the ber shows that in addition to the element of pectic cellulose, there prevails an unusual proportion of oil wax constituents, the natural balance ofwhich forms an important element of its spinning properties, but these valuable fiber elements are disturbed or entirely lost by artificial processes of retting, also, in the most favorable natural conditions by exposure on the ground, in the capricious climates, where it is impossible to control the injurious effects of the weather when it is spread upon the field; while all attempts to secure desirable conditions of the stalks or the fiber by the direct application of heat, are positively 1njurious as the heat causes irreparable injury of the ber, and coagulates the gums that hold the woody elements and fiber bound together, which will prevent complete separation and cleaning in the decortication. By my present method these objections are removed.

Oxidation of some of the constituentspf the agglutinating materials, such as resins and oils, in the hemp stalk, begins, and they Specicaton of Letters Patent.

Patented .ruiy i7, iai?.

Serial No. 45,161.

oXidiZe and change color at surprisingly low temperatures. This discoloration may begin at as low temperature as 75O or 80 F. though the effect at this low temperature is comparatively slight. However, as the tem-v perature rises, the darkening effect of the orridation rapidly becomes enhanced. The discoloration thus produced is transmitted in some degree to the fiber, making the fiber darker than it would otherwise be. This phenomena is not restricted to hemp fiber; but is known to exist whenever fiber is eX- posed, or vegetable matter of any kind. It may be seen in drying fruits. If the fruits are dried, immediately after being cut, at a low temperature, they dry very much brighter than if high temperature be used. A piece of apple will begin to turn dark almost as soon as it is cut if the room is at all warm, while in the cooler air out-ofdoors, it will keep much brighter. I aim to take advantage of this fact in curing my hemp stalks, and to keep the temperature of my drying atmosphere as low as possible, and preferably below 75O F. for the most part.

Another feature to be considered in this connection is the fact that the vegetable albuminoids begin to coagulate at temperatures not more than 1500. The coagulation may be coincident and simultaneous with the drying, and may serve to fix the coloring matter upon the fiber to some extent.

Another feature to be considered is that the curing air should be vas free from moisture as possible in order to remove the moisture at once from the fiber and to prevent the discoloring effects of the moisture from hydrolysis or other action.

Finally by keeping the temperature low, as indicated, and by effecting the practical exclusion of moisture I inhibit the growth of these fungi and bacteria, which are peculiar to the ancient process of retting, and in fact l keep down the growth of all such organisms, which have a discoloring e'ect, to as great an extent as possible.

It is, of course, obvious that the temperature of the air should be not carried so low that its moisture-removing capacity is nullified, or even greatly reduced.

One of the features of my process is the arrangement of the masses of hemp in such relation to volumes of moisture-removing air that the air is freely distributed among the hemp sheaves or bundles, and its edect thereby greatly enhanced. I may achieve this either by passing the air past the hemp or by moving the hemp through the air, or both. Relative motion of the two is desired merely.

Afterv many years practice in the art and thorough investigation of the subject with large experience in the production of fiber commercially, to supply the various conditions wanted by spinners, I find it is important on economic grounds, to carefully preserve and improve the natural excellence and working qualities of the ber in the operation of converting it to spinning purposes, and my present invention is conducive to novel results to this end.

It is usual to subject this fibrous plant to a preliminary treatment before crushing the stalks, by exposure in water or on the ground, vor by various chemical processes, with the Object of facilitating the separation of the liber from the non-fibrous gummy elements with which it is associated that bind it together, which consist of a glutinous substance Vthat by my present desiccating method yof first treating the whole unbroken fiber stalk, is crystallized and made brittle or fragile, and is easily pulverized to a dust without injury to the fiber, as when the desiccated unbroken stalks pass through the rollers of the decorticating machine, the woody portion and the white line dust of the gummy matter become separated and yield readily to the vbrake action, leaving the unbroken whole fiber soft, and clean, and free from all foreign matter, with its natural oily wax constituent undisturbed and preserved, and in vthe best condition "for spinning. My vvnov'el'process of desiccating the unbroken straw, `and crystallizing the incasing gums, whichl forms the subject matter of the present invention, does not consist in subjecting it to direct heat, but rather, to theabsorbent effects of dry air of any temperature, which I have demonstrated commercia'lly` as being superior to all other known methods.

LMy process protects and saves, and also 'improves the liber in its unimpaired condi- 'tion while on its natural stalk, thus retaining vfits oily constituents that preserve its weight "and tensile strength in converting 'the raw material into fiber, avoiding all rintervening expense of handling the straw,

and producing Vthe liber, as hereinafter vvshown and 'described The Ifiber lies under the bark, or epidermis, and outside "of the stalk to which it is closely bound by the 'eambium glutinous layer whichconnects the bast with the wood f thatfis to be removed, and the bast reduced 'to ya fiber, vwithout injury.

This vis a delicate operation, and Vhas de- 'ied'the many experimenters, and resulted `in a total failure, as it is a well known fact that any artificial process of drying the straw superficially by heat, hardens it and injures the liber, and operates to prevent its complete separation from the stalk and glutinous gummy substance.

rlhe thorough extraction of all moisture requires treatment by desiccation, which treatment prevents the humidifying iniuence of the atmosphere, while in the process of decortication.

The ber, not having been subjected to the effects of hydrolysis, nor exposed to atmospheric influences, is thus preserved in its natural state, and the brittle condition imparted to the gummy substances and wood, by its thorough desiccation while on the whole unbroken stalk, permits the most perfect separation of the fiber therefrom, as the stalks are crushed and cleaned by the decorticator.

To carry out my improved method. of exsiccation, I provide two or more independent compartments, connected with each of which is a circulating dry air system, having means for maintaining the proper temperature, which must not be hot, and establishing the circulation of desiccated air.

In the drawings, Figure l is a vertical, longitudinal, sectional view of a compartment, showing the connections of the circulating air system. Fig. 9. is a side elevation of same, or view of the desiccating compartments and showing a bundle of dry hemp stalks under treatment. Fig. 3, shows the manner of transporting the bundle of dry whole natural stalks through the process to the decorticator. Fig. el shows the mechanical decorticator reducing the desiccated stalks to a fiber.

Carriers, containing bundles of hemp straw, are supported on overhead tracks, in a well known manner, while different means may be employed to carry out my improved process, which is continuous in operation.

I show a conduit located beneath the com*- partlnents, containing the main air inlet pipe, while overhead, is the return main, which forms the circulating system, not fully shown in the drawing. At a distance from the compartments is an apparatus to produce the desired temperature, and means for establishing a circulation, and maintaining and controlling the same for desiccating purposes by a current of dry air, from which all moisture has been absorbed, as distinguished from evaporators, or kiln drying heat, and the separation cf the moisture from the gums is effected while the material is in continuous process of passing through the desiccating chamber, the gumm'y substances becoming crystallized, and will separate from the liber in form of dry dust Vunder the action of the vdecorticating machine as it crushes the whole stalk.

ln carrying out my process, it will be understood that it is not limited to any particular form of desiccating apparatus, as illustrated herein, which is merely indicative of one type that may be employed, and I have not specifically alluded to the mechanical features, nor designated the same by ier., ence letters.

While capable of a wide range of application, the present invention is designed for desiccating bundles of unbroken brous stalks, preparatory to decortication.

What I claim as my invention and desire to secure by Letters Patent,

l. A method of curing unretted fibrous stalks comprising the conveying of said stalks in suspended bundles and continuously passing them through desiccated air at ordinary atmospheric temperatures in an inclosed chamber to render the binding gums brittle and thereafter subjecting said stalks to mechanical decortication.

2. A method of preparing brous stalks for decortication consisting in renderingI brittle the gummy substances thereof by subjecting said stalks to desiccated air in motion at ordinary atmospheric temperatures while maintaining said stalks substantially free from contact with any7 conveyer to allow the circulation of the desiccated air on all sides.

3. A method of preparing fiber stalks for decortication which consists in rendering brittle the adhesive gums thereof by subjecting said stalks to desiccated air effects while said stalks are supported in moving relation to said air at, or below, ordinary temperatures.

4t. A method of preparing fiber stalks for decortication consisting in rendering brittle the adhesive gums thereof by subjecting said stalks to the curing eect of a dry cool moisture-removing atmosphere, while establishing a condition of relative movement between said atmosphere and said stalks.

5. A method of obtaining clean dried iibers from hemp stalks, which consists in curing the stalks rapidly in a cool atmosphere until the adhesive gums, which unite the fibers to the wood, become brittle, and then breaking the stalks to break up the wood and crumble the gums.

6; A method of obtaining ber from hemp stalks which consists in rapidly cooling such stalks with free circulation of cool air therethrough, under conditions which permit removal of moisture, whereby the adhesive gums of said plants become brittle, and crumbly, and inall breaking the stalks.

7. A method o obtaining fibers from hemp stalks, which consists in curing stalks of mature hemp rapidly in a cool atmosphere, and maintaining rapid circulation of said atmosphere in relation to said stalks, whereby discoloration and deterioration of the liber is prevented, and removing the iiber from the stalks.

CHAS. COLAHAN.

Witnesses:

M. H. COLAHAN, LEE C. REED.

Copies of this patent may be obtained for ve cents each, by addressing the Commissioner of latents, Washington, ZD. C. 

